Windows Media Encoder x64 Edition
Windows Media Encoder is one of the few popular video encoding tools that uses four threads to take advantage of quad-core systems, and it comes in a 64-bit version. For this test, I asked Windows Media Encoder to transcode a 153MB 1080-line widescreen video into a 720-line WMV using its built-in DVD/Hardware profile. Because the default "High definition quality audio" codec threw some errors in Windows Vista, I instead used the "Multichannel audio" codec. Both audio codecs have a variable bitrate peak of 192Kbps.

We keep varying the tests and trying new things, and the Core 2 processors keep beating the Athlon 64s. This time around, the Core 2 Quad Q6600 finishes 20 seconds before the Athlon 64 FX-74.

LAME MP3 encoding
LAME MT is the multithreaded version of the LAME MP3 encoder that we discussed earlier. LAME MT was created as a demonstration of the benefits of multithreading specifically on a Hyper-Threaded CPU like the Pentium 4. (Of course, multithreading works even better on multi-core processors.) You can download a paper (in Word format) describing the programming effort.

Rather than run multiple parallel threads, LAME MT runs the MP3 encoder's psycho-acoustic analysis function on a separate thread from the rest of the encoder using simple linear pipelining. That is, the psycho-acoustic analysis happens one frame ahead of everything else, and its results are buffered for later use by the second thread. That means this test won't really use more than two CPU cores.

We have results for two different 64-bit versions of LAME MT from different compilers, one from Microsoft and one from Intel, doing two different types of encoding, variable bit rate and constant bit rate. We are encoding a massive 10-minute, 6-second 101MB WAV file here, as we have done in many of our previous CPU reviews.

With only two threads at work, the fastest dual-core solution grabs the top spot, and that's definitely the Core 2 Extreme X6800.